general question on speed using quad core Xeons

[amjad ali]

Hello Petsc team (especially Satish and Barry).

YOU SAID: FOR Better performance

(1) high per-CPU memory performance. Each CPU (core in dual core systems)
needs to have its own memory bandwith of roughly 2 or more gigabytes.

(2) MEMORY BANDWDITH PER CORE, the higher that is the better performance you
get.

>From these points I started to look for RAM Sticks with higher MHz rates
(and obviously CPUs and motherboards supporting this speed).

But you also reflected to:

http://www.intel.com/performance/server/xeon/hpc_ansys.htm
http://www.intel.com/performance/server/xeon/hpc_md_nastr.htm

On these pages you pointed out that: systems with CPUs of 20% higher FSB
speed are performing 20% better. But you see also RAM speed is 20% higher
for the better performing system (i.e 800MHz vs 667 MHz).

So my question is that which is the actual indicator of "memory
bandwidth"per core?
Whether it is
(1) CPU's FSB speed
(2) RAM speed
(3) Motherboard's System Bus Speed.

How we could ensure "memory bandwith of roughly 2 or more gigabytes" per CPU
core? (Higher CPU's FSB speed, or RAM speed or Motherboard's System Bus
Speed).

With best regards,
Amjad Ali.






On 4/16/08, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>
>   Cool. The pages to look at are
>
> http://www.intel.com/performance/server/xeon/hpc_ansys.htm
> http://www.intel.com/performance/server/xeon/hpc_md_nastr.htm
>
> these are the two benchmarks that reflect the bottlenecks of memory
> bandwidth.
> When going from dual to quad they get 1.2 times the performance, when one
> would
> like 2 times the performance.
>
>   Barry
>
>
> On Apr 16, 2008, at 9:27 AM, Satish Balay wrote:
>
> > Just a note:
> >
> > Intel does publish benchmarks for their chips.
> >
> > http://www.intel.com/performance/server/xeon/hpcapp.htm
> >
> > Satish
> >
> >
>
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